Fix 1: Qualitative analysis of operator 15A.

Signed-off-by: cyberzhg <cyberzhg@gmail.com>
Fix 3: Qualitative analysis of operator 22.

Signed-off-by: cyberzhg <cyberzhg@gmail.com>
Fix 4: Qualitative analysis of operator 20.

Signed-off-by: cyberzhg <cyberzhg@gmail.com>